The BGA IC device has a plurality of bump electrodes on the bottom surface of a package, the bump electrodes being arranged in a grid pattern. The ordinary BGA IC device has the electrodes only on the bottom surface of the package and accordingly has no electrodes on the top surface of the package. On the contrary, there is known a device having electrodes on the top surface too in addition to the bottom surface. Such a device will be referred to as a double-sided electrode type hereinafter. The double-sided electrode type BGA IC device is disclosed in the first and second patent publications mentioned below.
First Patent Publication: Japanese Patent Publication 2003-124439 A.
Second Patent Publication: Japanese Patent Publication 2000-243867 A.
FIG. 15 is a front sectional view of one example of the double-sided electrode type BGA IC device. An IC device 10 has a package 13 which has a flat bottom surface 12 provided with a plurality of bump electrodes 14. On the other hand, the package 13 has a top surface which has a central protrusion 30 and a peripheral portion 32 surrounding the protrusion 30. The peripheral portion 32 is lower than the protrusion 30 by one step. The protrusion 30 contains an IC chip therein. The peripheral portion 32 is provided with a plurality of electrodes 18 (which will be referred to as upper electrodes hereinafter). Such a double-sided electrode type BGA IC device 10 can support, on its top surface, another BGA IC device 20 stacked directly on the device 10 so that the two devices can be connected to each other. Namely, bump electrodes 22 on the bottom surface of another IC device 20 are connected to the upper electrodes 18 of the IC device 10 so that the two IC devices 10 and 20 are fixedly connected to each other. If the upper IC device 20 is of the double-sided electrode type too, it is possible to stack BGA IC devices in three or more layers.
Incidentally, regarding installation of the BGA IC device to an IC socket for testing it electrically, two methods are known: one method is installation of the IC device directly to the IC socket; and the other method is mounting the IC device on an IC carrier and installation of the IC carrier along with the IC device to the IC socket. The latter method is better for especially a thin IC device because it can be handled under the protected condition. The present invention is concerned with the latter installation method. The following third and fourth patent publications disclose installation of the BGA IC device to an IC socket while the IC device is mounted on a carrier.
Third Patent Publication: Japanese Patent Publication 2000-266808 A.
Fourth Patent Publication: Japanese Patent Publication 2000-323249 A.
The third and fourth patent publications disclose that the ordinary BGA IC device having electrodes only on the bottom surface is mounted on an IC carrier and thereafter the IC carrier along with the IC device is installed to an IC socket.